As you enter a new stage in your life -- be it a brand-new relationship or the arrival of your newborn -- it's a good time to re-evaluate your contraceptive options, so you can decide on the birth control that best suits your lifestyle now. (Note: Before you change your contraception or stop taking it, consult your gynecologist -- one 15-minute chat can help you choose the one that's right for you.)

If you have a new partner...

It doesn't matter whether you're 25 or 45. When you're starting things up with a new sexual partner, your only safe contraceptive is the condom because it protects you against sexually transmitted diseases. "You use a condom not only to protect against pregnancy, but because it is possible for any sexually active person to have an STD and not know it," explains Beverly Winikoff, M.D., M.P.H., author of The Whole Truth About Contraception. "Many STDs have no symptoms, especially in the early stages. It is simply common sense to protect yourself and your partner."

If you are in a monogamous relationship...

You have moved onto the next stage in a relationship -- you're mutually faithful and you've both been tested and cleared for STDs. You can continue to use condoms at this point, or depending on your preferences, you might want to consider another contraceptive method. Some options have additional health benefits you may want to take advantage of, such as reducing period-related woes (including headaches, cramps, heavy flow, bloat and breast tenderness):

Birth control pills: Combination pills have the added bonus of helping with breakouts. Try it if you have acne, and don't smoke. (Smokers on the Pill increase their risk of blood clots, heart attack, and stroke.)

Birth control shot: Contains progestin and is given four times a year (every 11 to 13 weeks) to help prevent pregnancy. It may result in light or no periods. Try it if you have severe PMS or heavy flow or forget to take daily pills.

Hormonal IUD: A tiny T-shaped plastic piece is inserted into the uterus which releases the hormone levonorgestrel to protect against pregnancy for as long as five years. Additional benefits include reduced bleeding and cramps. Try it if you want to postpone having kids long-term.

If you plan to have a baby soon...

It may be best to use a contraceptive method that does not delay your return to fertility if you plan to start a family with your partner. Experts recommend stopping hormonal methods of contraception roughly one month before trying for a baby -- or even earlier in the case of contraceptive injections. "A number of months may pass after the last injection before fertility is restored," says Winikoff.

If you just had a baby...

You can take the Pill again 21 days after having a baby, but if you want to breastfeed, don't take the combination pill as it can reduce your milk flow. Try the progestin-only pill instead. Breastfeeding itself is also a very effective method of contraception if you're breastfeeding exclusively -- meaning you're nursing regularly without missing any breastfeeds and you have no periods.

If you do not want any more children...

It may be worth considering a permanent method of contraception such as sterilization, but you must be 100 percent sure that you do not want any more children before opting for this method. In a woman, it is done by blocking the fallopian tubes to prevent an egg being carried to the womb. In men, vasectomy blocks the tubes that carry sperm from the testicles to the penis.